Brush holder



' Sept. 21, 1948.

a. G. BLUEMINK BRUSH HOLDER Filed April 10', 1946 4 w 9 g 2 OOfl 4 7 6 2Q Z 2 1 j 2 b w 3 w a O 1 .l w A FM 1 3 ,5 .PIN flu, 7 2 3 A w 1 w w x w w v 3 3 1 i 1 Patented Sept. 21 1 948 BRUSH HOLDER Gary ,G. Bluemink,"jRacine, :WiS. .assignor to'Th Dumore Company,='- Racine; Wis a of wi-sconsin corporation .Application April. 10, IQ LGnSQriaI-NO- loclaims.

'1 This invention relates to improvements .Lin brush supporting construction .ifor electrical motors.

In the usual form of brush supporting Construc tion, the brush forms apart of aibrushassembly,

the parts of which are of current conducting material. Since themotori housing is also. .oicurrent conducting material, the brush assemblyLis mounted in an insulating holder. .The' brushessembly includes a spring which urgesthe" brush into electrical contact withthe commutator .cf the motor, and since means must be provided against which the springcan react, the brush assembly includes a, removable brush cap. which is generally threaded on to the .brushholder arid which serves to confine the spring. The brush cap may be removed .to permitreplacementcf the brush and itsassociated parts.

In thisusual form of construction, meanssujch as a set screw or the like, are provided toan'clhor the brushholder with respect to the motor housing, so that the force exerted'by the spring on the brush cap will not eject the brush holderand the brush assembly fromthe motorihousing,

It is an object of my invention toprovideia brush supporting construction which "eliminates the necessity of anchoring the brush holder in the motor housing by a setscrew orthelikemeans. Thus, the .cost of the brush supporting; construction is reduced, and the assembly,.ofrtheparts is facilitated.

Furthermore, in brush holders of the ordinary type, it is possible to forceihe "inner 3 sleeve through the insulatingsleeve sothati'the inner sleeve presses against the commutator, which may not only look therotor andpreventitfrom rotating, but may also-damage thecomm-utator. It is an object of my invention to provideia construction that will eliminate this possibility.

A further object is to proviclea fiush'mounti-ng, that is, a brush'supporting construction wlrlch does not project from the" motor-"housingtoany appreciable extent.

A further object of my invention is to "provide-a construction that is not only "waterproof but-aiso explosion-proof.

A still further-object --is to-provide aconstruction that will afford a much bettericonnectlon between the brush and the-conducting sleeve than is achieved with the usual construction.

Still another object is to provide a; brush 'supporting construction which includes-an insulating brush holder which is not threaded. Th-us, a less :costly construction fis -provided asvw-ill be pointed out hereina-tier.

That ;,embodiment-of myinvention which is hereinshown and described is known as a shunt brush construction inasmuch as the brush is connected into .the motor circuit by means of a shunt or pig tail, rather than through the brush spring. In-this connection, it isafurther object. of my --inventionto provide an improved shunt brush construction in which certain parts are locked against rotation, to the endthat the pig tail will notbe twisted when the brush plug is screwedinto position.

Itewillbe understood however, that my in- .vention is-equally applicable to'non shunt brush constructions, and. in either event, positive electrical con-tact between the current carrying parts is provided.

Q ther objects, features and advantages will become apparent as the description proceeds.

,With reference now to the drawings, in which likereference numerals designate like parts,

iiFig. 1 is,,.a.central sectional elevation through an electric, motor embodying a preferred embodiment of my invention;

Fig..,2j.is a perspective view of the brush assembly;

l'Eig..3 is a partial viewsimilar to Figbut slziowing theiparts in achan d po t n; a

"Fi A. is ,a ection taken alon line .4-,.4 of Fi 1.

With reference new tofFi .1, h r feren numeral l0 designates generally an electric nio- .tor having .two housing members ll and I2, which. together with other parts ofthemotor, not shown, may be. held, to etherby means of screws l3. in ,theusual ,manner. .The motor also .includesthe usual armature shaft Manda bearing l5. and c mmutator ywhi -m un o the armature shaft ..'Ihe. housing member ills fa .dielcast ,end piece whichisprovided with .a bore Hand acounterboneulfl, so as to provide .an outwardly facing shoulder I9. "Thelcdunterbore i8 s p ovi with .threadsin.

iA'ibrush holderziis disposed within the bor nd counterbore 1'1 and 18. 'The. brush holder is a composite member comprising two concentric sleeves}! and 24. .The outer sleeve 211s formed ofjinsulating material such ,as' Bakelite, and is prov ded-with.anangeH which en ages and seats against the shoulder l9. Thus, the longitudinal position of the brush holder 23 may be determined. "The conducting sleeve 24 is preferably made of brass and extends beyond both the up er and lower edges of the insulating sleeve 21. The parts are" preferably press fitted one into the other, and the conducting sleeve 24 is provided with a flange 25 which seats against a shoulder 26 formed in the flange portion of the brush holder 23.

A brush assembly indicated generally by the reference numeral 21 is disposed within the brush holder. It will be understood that the parts herein described which are related to the brush supporting means, including the bore and the counterbore, and the parts disposed therein, are provided in duplicate, as shown in Fig. 1, there being no distinction drawn between the two, insofar as this invention is concerned.

The brush assembly 21 comprises a brush 28, a shunt cap 30, and a pig tail 29, the opposite ends of which are secured to the brush and to the shunt cap in current carrying relationship. The

brush may be of the usual carbon composition, and one end of the pig tail is embedded therein. The other end of the pig tail may be soldered to the shunt ca as indicated by the reference numeral 35. A spring 3| surrounds the pig tall 29 and is confined between the shunt cap and the brush.

The sleeve 24 is provided with a bore 32 having oppositely disposed channels 33, so as to accommodate a brush of rectangular cross section. These channels, in their upper portions, also receive a pair of depending arms 34 forming a part of the shunt cap 30, thus locking the shunt cap against rotation with respect to sleeve 24. Thus, there is no possibility of twisting the pig tail.

A plug 36, having screw threads 31, is threaded into the threaded counterbore l8, and thus serves to urge the laterally extending portions 38 of the shunt cap against the upper edge of the sleeve 24, a shown in Figs. 1 and 3, thus providing an electrical contact. At the same time, the brush holder 23 is in turn urged downwardly to the limit of its motion, as determined by the flange 22 and the shoulder 9.. Thus, the parts are positioned with respect to the housing member |2, without the necessity of any set screw or the like.

As shown in Fig. 4, the shoulder 19 is provided with upset portions 39, which may either be formed by a staking tool or the like, or which may be formed in the casting process, so that when the holder 23 is initially urged downwardly, the upset portions 39 will bite into the relatively softer material of which the insulating sleeve, 2| is formed. Since the conducting sleeve 24 cannot rotate within the insulating sleeve 2|, due to the press fit between them, and since the insulating sleeve cannot rotate with respect to the housing I2, due to the locking effect of the upset portions 39, the entire brush holder 23, including its parts, are prevented from rotating. Thus, the rectangular brush 28 is always maintained in its desired angular position with respect to the commutator, without the use of a set screw. If desired, the under portion of the flange 25 may be provided with upset portions which bite into the shoulder 26 of the insulating holder, rather than resorting to the press fit above described. Similarly, other means such as suitable keys, may be employed to secure the parts against relative ro-' tation.

In initially assembling the device, the sleeve 24 is pressed into the holder 23, and the parts are then inserted into the bore and counterbore so that the longer transverse dimension of the brush opening is parallel to the axis of the armature shafts. A slight amount of pressure at this time is suflicient to cause the upset portions 39 to bite into the flange 22, so as to secure the parts against relative rotation. The brush assembly, comprising the brush 28, the pig tail 29, the shunt cap 30, and the spring 3| are then inserted into the sleeve 34, and the plug 36, which is recessed to accommodate the upper portion of the sleeve, is then threaded into the counterbore l8. As the plug is tightened up, the spring 3| is compressed, so that it will urge the brush 28 against the commutator I6 in the usual manner. The parts are so dimensioned that a slight clearance 40 is provided between the plug and the upper edge of the insulating sleeve 2|, because the limit of the in sertion of the plug should be determined by its engagement with the shunt cap 30 in order to provide satisfactory electrical contact between the shunt cap and the sleeve 24.

The plug 36 is formed from a suitable insulating material, and it will b seen that the current carrying parts of the brush assembly 21 are insulated from the housing member |2 by means of the plug 36 and the holder 23. By arranging the parts in the manner shown, so that the screw threads of the plug directly engage the housing member, rather than the insulating holder, as in the prior art, I am enabled to provide a much less costly construction. This is because I eliminate the set screw formerly used, and I also eliminate the screw threads on the insulating sleeve. Due to the difllculty and the expense of threading the Bakelite or other material of which the insulating sleeve is formed, the saving effected by the elimination of the threading operation is substantial.

It will be evident that by eliminating the pig tail, the usual non shunt construction may be employed if that is desired. In this instance, the current passes from the brush to the shunt cap through the spring 3|. Connection to the field circuit may be efiected in the usual manner by attaching a conductor to the lower portion of the sleeve 24, and as shown in the figures, grooves 4| are provided to facilitate this connection.

I do not intend to limit the housing member I2 to a die casting; it may be formed from any suitable material by any suitable process. Similarly, the bore I? need not necessarily be of circular cross section. For instance, it may be of rectanguliar cross section, and the insulating sleeve 2| may be of a corresponding shape. In such an instance, the shape of these parts will prevent relative rotation between the brush holder and the housing. and the upset portions 39 may be eliminated. It is understood that the term bore as used herein may indicate a cavity or aperture of any desired cross sectional shape.

The plug 36 may be removably secured Within the counterbore |8, or like aperture, by any'suitable means, the screw threads 31 and 20 being shown herein only by way of example.

Although only a preferred embodiment of my invention has been shown and described herein, it is obvious that various modifications and changes'may be made therein without departing from the spirit of my invention as defined in the appended claims.

I claim:

1. A brush supporting construction comprising a motor housing having an aperture, an outwardly facing shoulder in said aperture, a. brush holder disposed within said aperture, a flange on said brush holder engaging said shoulder to limit the inward motion of said brush holder with respect to said motor housing, means interlocking with the outer portion of said aperture and limiting the outward motion of said brush holder to maintain thesame in I a fixed position with respect to. said motor housing a brush slidably mounted inlsaid brush holder, and a spring confinedbetween said brushwand said interlocking means to urge said brush inwardly, said brush holder including an insulating sleeve to insulate sai-d brushfrom said motor housing.

2. A brush supporting construction comprising a motor housing having an aperture, an outwardly facing shoulder in said aperture, a brush holder disposed within said aperture, a flange on said brush holder engaging said shoulder to limit the inward motion of saidbrush holder with respect to said motor housing, a plug interlocking with the outerportion of said aperture and limiting" the outwar d'motion of said brush holder to-maintain the same in .a fixed position with respect to said motor housing, a brush of rectangular cross section slidably mounted in saidbrush holdenanda spring confined betweensaidbrush and'said plug torurgethe brush inwardly, said brush holderineluding a conducting sleeve-providing avrectangular opening for said brush and a surrounding sleeve of insulating material, said shoulder and said flange cooperating to prevent angular displacement of said brush holder with respect to said motor housing.

3. A brush supporting construction comprising a motor housing having a bore and a counterbore forming an outwardly facing shoulder, an insulating brush holder disposed in said bore and counterbore and having a flange seated against said shoulder, a plug removably secured within said counterbore and engaging said brush holder to maintain the same in a fixed position with respect to said motor housing, a brush slidably mounted in said brush holder, a spring confined between said brush and said plug, and a conductor extending from the top of said spring along the interior surface of said brush holder and extending beyond the lower edge thereof.

4. A brush supporting construction comprising a motor housing having a bore and a threaded counterbore forming an outwardly facing shoulder, an insulating brush holder disposed in said bore and counterbore and having a flange seated against said shoulder, means on said shoulder interlocking with said flange to prevent angular displacement of said brush holder, a plug threaded into said counterbore and engaging the upper portion of said brush holder to maintain the same in a fixed position with respect to said motor housing, a brush slidably mounted in said brush holder, and a spring confined between said brush and said .plug to urge said brush through the inward end of said bore.

5. A brush supporting construction comprising a motor housing having a bore and a threaded counterbore forming an outwardly facing shoulder, an insulating brush holder disposed in said bore and counterbore and having a flange seated against said shoulder, means on said shoulder interlocking with said flange to prevent angular displacement of said brush holder, a plug threaded into said counterbore and engaging the upper .portion of said brush holder to maintain the same in a fixed position with respect to said motor housing, a brush slidably mounted in said brush holder, and a spring confined between said brush and said plug, said brush holder including a conductor extending from the top of said spring along the interior surface of said brush holder and extending beyond the lower edge thereof.

6. A brush supporting construction comprising a motor housing having a bore and a threaded counterbore forming: an; outwardly facing shoulaumotor housing 'having'ya bore; and a threaded counterhore forming an 1 outwardly facing 1' shoulder;.a: brush holder disposed inx'said loore': and counterbore and havin a flange. seated: against said: shoulder;. said ishoulder' being provided" with upset. ortions whioh bite into said flange inv Zorder to prevent relative rotation or said brush holderand saidtmotor housing, a brush assembly disposed: within said brush holder; and-9: plug threaded into. said c'ounterbore, said lbrnsh assembly; including a shunt 1 cap which is r confined: between the upper edge of said brush holder and said plug, a brush slidably mounted in said brush holder, and a spring confined between said shunt cap and said brush, and said brush holder including an insulating sleeve and a conductor extending along the interior surface of said insulating sleeve, one end of said conductor bein in electrical contact with said shunt cap, and the other end extending beyond the lower edge of said brush holder in order to provide a terminal to which a conductor may be secured.

8. A brush supporting construction comprising a motor housing having a bore and a threaded counterbore forming an outwardly facing shoulder, a brush holder disposed in said bore and counterbore and having a flange seated against said shoulder, said shoulder being provided with upset portions which bite into said flange in order to prevent relative rotation of said brush holder and said motor housing, a brush assembly disposed within said brush holder, and a plug threaded into said counterbore, said brush assembly including a shunt cap which is confined between the upper edge of said brush holder and said plug, a brush slidably mounted in said brush holder, and a spring confined between said shunt cap and said brush, and said brush holder being a composite member formed from two concentric sleeves secured to each other, the inner sleeve projecting beyond both ends of the outer sleeve, and being formed of a conducting material, and forming said upper edge of the brush holder, and the outer sleeve being of insulatin material whereby said inner sleeve is insulated from said motor housing.

9. A brush supporting construction comprising a motor housing having a bore provided with a seat for a flanged sleeve, a brush holder comprising an insulating sleeve disposed in said bore and having a flange seated against said seat, said seat being provided with upset portions which bite into said flange in order to prevent angular displacement of said brush holder in said bore, a brush assembly disposed within said brush holder, and a plug threaded into said bore, said insulating sleeve being provided with a metallic lining which projects beyond said flange, said brush assembly including a shunt cap which is gripped between the upper edge of said metallic lining and said plug, a brush slidably mounted in said brush holder, a spring confined between said shunt cap and said brush, a pig tail connected at either end to said brush and said shunt cap, and means on said shunt cap interlocking with said metallic lining to prevent twisting of said pig tail.

10. A brush supporting construction comprising a motor housing having a bore and a threaded counterbore forming an outwardly facing shoulder, a brush holder disposed in said bore and counterbore and having a flange seated against said shoulder, said shoulder being provided with upset portions which bite into said flange in order to prevent relative rotation of said brush holder and said motor housing, a brush assembly disposed within said brush holder, and a plug threaded into said counterbore, said brush assembly including a shunt cap which is confined between the upper edge of said brush holder and said plug, a. brush slidably mounted in said brush holder, a spring confined between said shunt cap and said brush, a pig tail connected at either end to said brush and said shunt cap, and means on said shunt cap interlocking with said brush holder to prevent twisting of said pig tail, said brush holder including an insulating sleeve and a conductor extending along the interior surface of said insulating sleeve, one end of said conductor being in electrical contact with said shunt cap, and the other end extendin beyond the lower edge of said brush holder in order to provide a terminal to which a conductor may be secured.

GARY G. BLUEMINK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

